Protection Schemes
745
Transformer Management Relay
Commission
ing
http://www.GEindustrial.com/multilin
7–37
GE Multilin
3. Apply a voltage starting at 60 Hz and increase the magnitude until the element
operates. Reduce the frequency in steps of 5 Hz and repeat the measurement.
The element should operate at a consistent value of Volts/Hertz equal to the
setting of the element.
4. Check that the Trip and Pickup LEDs are on and one of the following trip
messages is displayed:
LATCHED: Volts-Per-Hertz 1
or
OPERATED: Volts-Per-Hertz 1
5. For timing tests, prepare a table of expected operating time versus applied V/Hz
signal from the selected timing curve for the element. Using the variable
frequency function generator to simulate the different V/Hz ratios, apply
suddenly to the relay and measure the operating time.
b) 5th Harmonic Scheme
The 5th Harmonic Scheme operates if the 5th harmonic content of any current
signal connected to the relay exceeds the threshold setting, for the set time,
provided that the level is above the set threshold.
1. Disable all protection functions except the 5th Harmonic function. The 5th Har-
monic scheme settings are in the
S4 ELEMENTS
!"
OVEREXCITATION
!"
5TH HAR-
MONIC LEVEL
setpoints menu.
2. This test requires a current generator capable of producing a fundamental and
5th harmonic component. Connect the current signal to H1 and G1 and set the
fundamental component level above the threshold setting.
3. Slowly increase the amplitude of the 5th harmonic component until the element
operates. Calculate the ratio of 5th harmonic to fundamental at which operation
occurred and compare this value to the setting of the element.
4. Check that the Trip, Pickup (and if selected, Alarm) LEDs are on, and one of the
following is displayed:
LATCHED: 5th Harmonic Level
or
OPERATED: 5th Harmonic Level
5. Reduce the 5th harmonic component until the element resets. The reset level
should be 97% of the operate level. Reset indicators and clear messages.
6. Repeat the above steps with a fundamental current level below the threshold
setting. Ensure that the element does not operate.
7. For timing tests, simulate an operating condition as above and apply suddenly
to the relay and measure the operating time. The time should be the same as
the setting in the element.
Insulation Aging
a) Description
The three elements under the Insulation Aging feature,
Hottest-Spot Limit
,
Aging
Factor Limit
, and
Loss of Life Limit
, must be tested with a valid set of transformer
data programmed into the relay. The ambient temperature must also be
programmed (obtained from an RTD or programmed as 12-month averages). The
tests consist of simulating transformer loading by applying a current signal to
Winding 1 Phase A at the correct frequency.
b) Hottest-Spot Limit
The hottest-spot temperature value is a function of load, ambient temperature, and
transformer rating. Apply a current to Winding 1 Phase A to represent at least a
100% load on the transformer. Use the
A2 METERING
!"
LOSS OF LIFE
!
HOTTEST-SPOT
WINDING TEMPERATURE
actual value to observe the hottest spot temperature
increases gradually. The simulated load to may be increased for a faster
temperature rise.
When the hottest spot temperature reaches the
S4 ELEMENTS
!"
INSULATION AGING
!
HOTTEST-SPOT LIMIT
!"
HOTTEST-SPOT LIMIT PICKUP
operating level, the element should
operate. Verify all programmed relay operations as per FlexLogic™ settings. Verify
that all the targets and messages are as expected and programmed.
Summary of Contents for Multilin 745
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